i am looking to add a washer machine to my basement, but connecting the drain to the horizontal run i don't have 18" from the top of the horizontal drain to to the top of a stand pipe. So I was wondering if i could tee in where the C/O is, put a C/O after the new tee and the I would have room for a trap and AAV for my washer drain. the standpipe that you see in the picture is for a water softner drain. Any suggestion would be appreciated
